The present invention relates to a golf clubhead and a manufacturing method therefor, and more particularly to an internal structure of the hosel portion of the golf club head which is capable of providing greater flexibility in the designing of the golf clubhead.
In recent years, there is a tendency for the wood-type golf clubs to increase the size or volume of the clubhead. Although the volume of the clubhead is increased, the weight of the clubhead should not be increased. In designing such a wood-type golf clubhead, a target weight and target volume of the clubhead are usually first given, and the position of the center of gravity of the clubhead, which greatly affects the position of the sweet spot, moment of inertia, performance, feel and the like, must be determined relative to the club shaft. In a conventional wood-type metal head whose volume is not so large, an extension of the hosel which is usually provided in the clubhead is formed as a protuberance extending along the inside of the clubhead as shown in FIGS. 13a and 13b. In this structure, if the head volume is increased and as a result it becomes necessary to shift the hosel portion towards the center of the clubhead, the protuberance becomes large and the weight is increased in this part. As a result, it becomes very difficult to adjust every design parameter to the desired target value. To satisfy one parameter, it becomes necessary to sacrifice another parameter. For example, the head volume is decreased to achieve the position of the center of gravity. Thus, it becomes very difficult to freely design such a clubhead.
It is therefore, an object of the present invention to provide a golf clubhead and a method of manufacturing the same, which can provide greater flexibility in designing the golf clubhead, and thus provide a clubhead of high-performance.
According to one aspect of the present invention,
a golf clubhead comprises a main body and a face member, the main body comprising a main shell portion having a hollow and a tubular inner extension of a hosel protruding in the hollow, and at least a part of the tubular inner extension separating from the inner surface of the main shell portion. A method of making the golf clubhead comprises making a first lost form corresponding to the main shell portion, making a second lost form corresponding to the tubular inner extension, fixing the second lost form to the first lost form to make a third lost form corresponding to the main body, making a casting mold using the third lost form, and casting a metallic material into the main body using the casting mold.
Therefore, weight can be saved in the hosel part. As a result, greater flexibility in designing the clubhead can be obtained. For example, it becomes possible to shift the position of the center of gravity towards the toe. Further, the saved weight can be utilized for: lowering the position of the center of gravity; increasing the volume of the clubhead; increasing the moment of inertia of the clubhead; increasing the strength or durability by distributing to a weak part; and the like.